A shoving match broke out in a most unlikely place, the typically serene Minneapolis Institute of Art, where three people who appeared to be neo-Nazis fought with several others in another group of activists, a witness said Sunday.

Security guards arrived at the mayhem Saturday afternoon on the museum's third floor, broke up the confrontation and had one of the reputed neo-Nazis on the floor, said museum visitor Will Bildsten.

A friend of Bildsten's said he saw punches thrown during the fracas.

Institute Director Kaywin Feldman said some of those involved were with about two dozen people protesting outside in opposition to anti-immigration sentiment in the U.S. They hoisted a banner with slogans in Spanish and English: "Una clase, una lucha — contra fronteras [one class, one struggle — against borders]!" and below that, "Don't deport our fellow workers."

Fliers handed out by the protesters outside identified the participants as with the defense arm of the Industrial Workers of the World union.

When the group said to look like neo-Nazis entered the admission-free museum, several from the protest outside followed, Feldman said.

They made their way to the third floor amid the 18th century European art, where the tension turned physical, the director said. She said one person among the trio was attacked but didn't want to press charges.

In the eight or so minutes that the clash lasted, Feldman said, no artwork was damaged.

"Our security did an incredible job disarming the situation and did exactly as they were trained to do," Feldman said.

Police officers called to the museum at 2400 3rd Av. S. made no arrests but did confiscate a large knife from one person, according to a police incident report. Feldman said police were reviewing video surveillance from inside and outside the building.

Vijit Nanda, at the museum with Bildsten, said, "I heard voices that were louder than usual for a museum. There [was] a large man with a buzz cut arguing loudly with some people. They were getting in each other's faces and quickly started pushing each other." A security guard "standing right in front of the group called loudly for help into his radio. The people who were fighting started throwing punches."

Nanda said the scene "felt incredibly surreal and unsettling to see … in a place that is usually very silent."

As he and Bildsten were leaving that part of the museum, a group of people "dressed in mostly darker colors walked out in front of us chanting and pumping their hands in the air," Nanda said. "I honestly do not remember the exact words, but it was something along the lines of 'Nazi scum get off our streets!' "

Bildsten said he had just come up the stairs to the third floor when he saw "a lot of commotion, people arguing and pushing" amid the exhibit.

In one group were three men that Bildsten described as looking like neo-Nazis. He said one of them had a "neo-Nazi" or white nationalist symbol on the back of his jacket.

Bildsten said he heard some in the rival group yelling "you Nazi" and "you fascist."

"It was a huddle of people pushing and coming close to the art," Bildsten said, who witnessed four to five minutes of the incident. "The art is worth a fortune; very large, traditional paintings in that area."

Several visitors yelled at the combatants, Bildsten said. Once the guards broke up the clash, "The anti-fascists marched off in a line," he said.

Paul Walsh is a general assignment reporter at the Star Tribune. He wants your news tips, especially in and near Minnesota.